The present invention relates to isolation valves and pressure sensors. More particularly, the present invention relates assemblies for electrically outputting signal information regarding two or more pressurized fluid-containing lines, including isolation valves for each of the pressurized fluid-containing lines so the pressure sensors can be removed or replaced while the pressurized fluid-containing lines are shut off by the isolation valves.
Differential pressure sensors or differential pressure transducers are known in the art. The differential pressure sensors include at least first and second pressure inlet ports. The first (low) pressure inlet port may be attached to a low pressure inlet line and the second (high) pressure port may be attached to a higher pressure inlet line. The differential pressure transmitter returns an electrical signal indicative of the difference in pressure between the higher pressure line and the low pressure line. The differential pressure transmitter is intended to measure a difference in pressure with substantially no flow between the pressure lines. The transmitter may include a single diaphragm or other sensor element affected by the low pressure and the higher pressure on both opposing sides, or it may include two separate pressure sensors with the measured pressure low pressure electrically compared against the measured high pressure.
Such pressure sensors are most commonly supplied on a stand-alone basis. Installation in the field may require two or more individuals: an electrician to run the electrical lines and a plumber or pipe-fitter to run the fluid lines. Additionally, the plumber or pipe-fitter may install isolation valves on the ends of the low pressure line and the high pressure line to facilitate removal or replacement of the pressure sensor(s) or transducer(s). The isolation valves can be closed to close off or xe2x80x9cisolatexe2x80x9d the high and low pressure lines from the pressure sensor elements.
Differential pressure sensors assemblies or differential pressure transmitter assemblies are known in the art. These assemblies incorporate both the pressure sensor assembly and the isolation valve assembly as a single manufactured product, and thus require less field installation time. In particular, the connections made between the isolation valves and the pressure sensor(s) may be made as a manufacturing step for the assembly rather than in the field.
Known differential pressure transmitters may be assembled from relatively low cost components, but assembly and/or installation time and costs may be significant. Improvements are needed to reduce the cost and increase the functionality both in the manufacture and in the installation of such pressure transmitters.
The present invention is a pressure monitoring assembly primarily including an isolation valve assembly and a pressure sensor assembly. A rigid manifold has two pressure inlet ports which communicate with two pressure outlet ports through isolation valves. In one aspect, an equalization passage and valve are provided between the two pressure lines. The pressure sensor assembly is sized to mate directly with the monolithic manifold by having sensor inlet ports that line up with the pressure outlet ports. Pressure tight attachments releasably secure the pressure sensor assembly to the manifold. The present invention allows significant reductions in assembly and installation times. The present invention is much smaller than prior art assemblies, so bleeding valves are unnecessary. In another aspect, thermal transfer is effectively utilized so the smaller size does not significantly increase the amount of heat transfer between the pressure lines and the pressure sensor(s).